1. Field of the Invention
This invention relates to molded plastic electrical outlet boxes and, more particularly, to a plastic blank foldable from a generally flattened position to a folded erect position to thereby form an open-topped, three-dimensional electrical outlet box.
2. Description of the Prior Art
Junction outlet boxes are generally die cast or stamped out of metal. Molded plastic junction outlet boxes are also well known. Generally, the plastic outlet boxes are formed in one piece by a molding operation or the like. An electrical device such as a switch, electrical receptacle, convenience outlet or the like, is mounted by mounting screws in both types of boxes. For this purpose, tapped holes are provided in the metal boxes, and a user must turn the mounting screws all the way down with the aid of a screwdriver to securely mount the electrical device in place within the box. As for plastic boxes, although it has been proposed to provide similar tapped holes therein, stripping of the plastic threads against the metal screw threads has caused manufacturers to use metal inserts that have threaded holes, such as nuts or resilient legs. The insert with resilient legs is preferred since a user can mount the electrical device by pushing the mounting screw in direction lengthwise of the screw with the aid of a screwdriver without damaging the screw threads. Assembly time is significantly reduced because it is not necessary to turn these screws all the way in. Of course, the screws held by the insert must be fully turned out. The resilient legs of the metal insert generally dig into the screw threads when a pulling force is applied to the screws to thereby prevent unauthorized de-mounting.
Because of rigid industrial standards regarding the security of this type of assembly and the design limitations of the insert, such resilient legs generally wind up a considerable distance below the top surface of the outlet box.
Consequently, the effective length of the assembly mounting screws is considerably reduced. Moreover, in order to mold the flanges which contain the metal insert, a considerable amount of volume is taken up inside the outlet box. This, in turn, results in outlet boxes of greater depth in order to comply with industrial requirements for a minimum internal volume of an electrical outlet box. A further disadvantage of the conventional three-dimensional non-foldable plastic outlet box is the shipping cost and large storage space required due to the volume of each box.
Since the conventionl plastic outlet boxes are molded in a single piece, there was no way to provide a strain relief for an electrical cable which was to be inserted into the box. Moreover, the prior art has proposed knock-out sections on the box in order to provide an opening for entrance of the electrical cable. However, it was time consuming for an electrician, i.e., to break out the sections, and frequently a great deal of damage was caused to the structural integrity of the box. Also, it was necessary for the electrician to staple the cable to a beam outside of and in close proximity of the outlet box, another time-consuming operation.